1. Field of the Invention
The present invention is directed to methods for improving the feel and appearance characteristics of cellulosic-containing fabrics. In particular, the methods of the present invention are directed to applying a cellulase solution under pressure to cellulosic-containing fabric during the manufacturing process under conditions wherein the solution cascades over the fabric. When so conducted, the treated cellulosic-containing fabric has improved feel and appearance characteristics as compared to the fabric prior to treatment, which improvement is achieved in an efficient manner. Additionally, this process removes a portion of the immature cellulosic-containing fibers from the fabric which provides for further improvements in the quality of the so-treated fabric.
2. State of the Art
During or shortly after its manufacture, cellulosic-containing fabrics are generally treated in a manner which improves their appearance and accordingly their quality. One means of improving the appearance and luster of such fabrics is to treat the fabric with a caustic alkaline reagent, for example, sodium hydroxide, and the like. This process of treating fabric with a caustic is termed "mercerization" and provides beneficial results to the so-treated fabric including increased dye yield, and increased tensile strength, increased luster, and appearance. However, use of such caustic reagents raises handling problems and safety concerns.
The art, in general, also teaches the application of cellulase enzymes to cellulosic-containing fabric to enhance the feel and/or appearance of the fabric. Such applications are described, for example, by Cox et al., U.S. Pat. No. 5,232,851, which discloses methods for treating non-dyed and non-finished cotton woven fabrics with a cellulase solution with agitations and under conditions so as to produce a cascading effect of the solution over the fabric. When so treated, improvements in feel and appearance are achieved under more efficient conditions as compared to treatment of the fabric with agitation only. Other fabrics heretofore treated with cellulase solutions under agitation and cascading conditions include cotton knits and cotton denims.
Notwithstanding the advantages and improvements achieved by treating cellulosic-containing fabrics with a cellulase solution with agitation and under conditions so as to produce a cascading effect of the solution over the fabric, the processes described by Cox, et al., U.S. Pat. No. 5,232, 851, and others nevertheless have reaction times which are undesirably long for an efficient manufacturing process. Moreover, while such processes reduce fabric strength loss as compared to processes which do not agitate and cascade the cellulase solution over the cotton-containing fabric, additional reductions in strength loss are desirable.
In any event, the above described methods of contacting cellulosic-containing fabrics during manufacture with a cellulase solution are contrasted with methods of cleaning fabrics with a laundry detergent composition containing cellulase because the cellulosic-containing fabrics employed in the methods described herein are treated during the manufacturing process, e.g., prior to application of a finish to the fabric.
In spite of the above described methods, there is a continuing need for methods to upgrade the quality of cellulosic-containing fabrics by treatment with a cellulase solution while reducing/minimizing the treatment reaction time, particularly during the manufacture of cotton woven fabric. Likewise, there is a need for methods to upgrade the quality of cellulosic-containing fabrics by treatment with a cellulase solution during the manufacturing process that are more efficient than the methods of merely cascading and/or agitation. It would be particularly desirable if such methods also resulted in fabrics having improved appearance and feel with minimal strength loss as compared to fabrics prior to treatment.